EP0004345B1 - Prestressed reinforced concrete cable and its application for manufacturing a suspension bridge - Google Patents

Description

The invention relates to a prestressed reinforced concrete rope in a covered concrete body laid in cladding tubes and prestressed steels injected after tightening with cement mortar.

Such prestressed reinforced concrete ropes are known for anchoring or suspending loads, and in particular also for the suspension ropes and suspension bars of suspension bridges (DE-A-1 941 978), since suspension bridges made of prestressed concrete, at least as far as maintenance of the bridge is concerned, are considerably cheaper are. It can already be seen today that the use of high-strength steels for steel suspension bridges and steel cable-stayed bridges is becoming increasingly critical, since these high-strength steels are much more susceptible to corrosion. Since it has so far not been possible to find economical processes and techniques in steel construction which permit a long installation of high-strength steels without the necessary and very cost-intensive measures for corrosion protection, the tendency to use prestressed reinforced concrete ropes is becoming ever greater. It turns out, however, that the use of prestressed reinforced concrete ropes meets with prejudice, particularly when building bridges, because there is still a risk of corrosion of the steel parts due to the use of road salt and the salt water penetrating the concrete. Further difficulties are also seen in the need for formwork, which has to be assembled and dismantled with relatively great effort.

For the anchoring of a tension member, in which tension members constructed from steel strands are partially arranged in a casing, which is injected with cement mortar after tensioning the tension members, it is already known (DE-B-2 114 863), this tension member while fanning out the steel strands to be inserted into the concrete part serving as anchoring. In a certain area before and after the entry of the tension member into the concrete part, a covering designed as a metal jacket is provided, which is injected with concrete mortar after tensioning the steel strands. The entire tension member running outside the anchoring is not constructed as a prestressed reinforced concrete rope, and is only provided with a sheath, preferably made of plastic, for the purpose of corrosion protection, but this has no supporting function.

Another known suspension cable of a cable-stayed bridge (DE-A-2 425 866) consists of a cable core which is guided in a cladding tube and around which a large number of tensioning strands are also arranged in cladding tubes. The cladding tubes are expediently made of plastic. The cladding tubes of the outside tension cables are fastened to the cable core with the help of clamps. To securely connect the inner cladding tube to the steel strands and the outer cladding tube to the tensioning strands, they are injected with cement mortar. A prestressing in the sense of a prestressed reinforced concrete rope does not take place. Embedding the cable core with its cladding tube and the tube bundle with the tension strands in concrete is only intended in the area of the anchoring.

The invention has for its object to provide a prestressed reinforced concrete rope in which the cladding tubes and the outer casing tube the reinforcement for the concrete body, i.e. form part of the load-bearing system, while at the same time the impairment of the reinforced concrete rope by the corrosion-promoting influences should be eliminated.

This object is achieved according to the invention in that the concrete body is surrounded by a corrosion-resistant outer casing tube made of sheet steel, which serves as lost formwork in the manufacture of the concrete body, and that the cladding tubes guided in the outer casing tube by intermediate bulkheads each consist of a steel tube which can be subjected to tension and pressure consist.

According to a further embodiment, for easier introduction of the concrete, it is provided that the outer casing tube is provided with tightly closable openings for introducing the concrete in sections.

The prestressed concrete cables manufactured according to the features of the invention can be used for suspension cables and suspension cables of a suspension bridge or for suspension cables of cable-stayed bridges. Such pre-stressed reinforced concrete cables manufactured according to the invention have the advantage that the casing pipe and the steel casing pipes represent the reinforcement for the concrete body, which together with the outer casing pipe has a very high buckling stiffness and practically cannot bulge. Another advantage is that the use of an outer casing tube means that both the cladding tubes and the prestressing steels drawn into the cladding tubes are very well protected against corrosion and dirt during the construction period and therefore have an intimate connection with the inserted concrete due to the good connection surfaces.

The invention further provides a method for the use of prestressed reinforced concrete ropes in the manufacture of a suspension bridge, which consists in that for the supporting ropes of the bridge the outer casing tube is suspended in sections with cladding tubes guided in bulkheads on the assembly rope guided over the pylons, so that the cladding tubes are thrown together and the outer casing pipes are screwed or welded to each other so that outer casing pipes with bulkhead-guided cladding pipes are suspended from the work platform for the suspension rods of the bridge, that prestressing steels are drawn into the casing pipes of the supporting cable and hanging rods, so that the interior of the outer casing pipe of the supporting cables and, if necessary the hanging bars it is concreted that the suspension ropes and the suspension rods are, if necessary, gradually pretensioned according to the load, that the longitudinal members of the bridge are suspended either in the free stem or as prefabricated parts on the suspension rods and that the cross members and the carriageway slab are then completed, and that the suspension ropes and the The suspension rods are pre-stressed and the cladding tubes are grouted by injection.

With such a method according to the invention, it is also possible to manufacture large suspension bridges from prestressed concrete, whereby the construction and dismantling of an elaborate formwork is omitted and an inclined suspension of the formwork for the supporting cables or a support of the formwork for the hanging bars is no longer necessary. Since the outer casing pipes are concreted before the longitudinal members and the carriageway slab are manufactured, both the suspension cables and the suspension rods can be pre-stressed to absorb point loads during the manufacture of the longitudinal members and the carriageway slab. By shrouding the cladding pipes made of steel pipes and welding the outer casing pipes, a support system is created even before concreting, which can easily accommodate the loads that are to be carried when concreting the suspension cables and suspension rods.

• Fig. 1 einen Längsschnitt durch ein vorgespanntes Stahlbetonseil gemäss der Erfindung vor dem Einbringen des Betons;
• Fig. 2 einen Schnitt längs der Linie 2-2 der Fig. 1;
• Fig. 3 eine schematische Seitenansicht einer unter Verwendung von vorgespannten Stahlbetonseilen gemäss der Erfindung hergestellten Hängebrücke;
• Fig. 4 eine Schnittdarstellung durch den Knotenpunkt zwischen dem Tragseil und einem Hängestab bei der Hängebrücke gemäss Fig. 3;
• Fig. 5 einen Längsschnitt durch eine verschraubte und verschweisste Stossstelle von Aussenmantelrohrabschnitten.

The advantages and features of the invention also result from the following description of an exemplary embodiment in conjunction with the claims and the drawing. Show it:

• 1 shows a longitudinal section through a prestressed reinforced concrete rope according to the invention prior to the introduction of the concrete.
• Fig. 2 is a section along the line 2-2 of Fig. 1;
• 3 shows a schematic side view of a suspension bridge produced using prestressed reinforced concrete cables according to the invention;
• FIG. 4 shows a sectional view through the node between the suspension cable and a suspension rod in the suspension bridge according to FIG. 3;
• Fig. 5 shows a longitudinal section through a screwed and welded butt joint of outer casing tube sections.

1 shows a section through a section of a prestressed reinforced concrete rope according to the invention, an assembly state with a retracted prestressing steel and before the concrete is introduced being shown.

In an outer casing tube 10, e.g. between 2 and 6 m, annular bulkheads 11 are arranged, through which cladding tubes 12 are guided along the outer edge region. These cladding tubes preferably consist of steel tubes with a relatively large wall thickness, which are connected in sections to sleeves 14. These sleeves 14 are preferably screwed onto external threads on the cladding tubes. A rod-shaped prestressing steel 16 runs through the cladding tubes in a conventional manner. Depending on the length of the reinforced concrete rope, this is built up in sections, the individual cladding tubes being connected with sleeves and the corresponding sections of the outer jacket tubes being welded. Such a welding is identified by reference number 18.

With such a construction, the outer casing tube 10 serves as lost formwork and is filled with concrete in its entirety. The cladding tubes made of relatively thick-walled steel tubes together with the bulkheads 11 represent a reinforcement that already gives the reinforced concrete rope an extraordinary strength and buckling stiffness. After prestressing the prestressing steels 16, the cladding tubes are then injected in a conventional manner, which completes the prestressed reinforced concrete rope.

A stainless steel is advantageously used for the outer jacket pipe, so that after the prestressed prestressed concrete rope is finished, it is optimally protected against corrosion and requires no maintenance to suppress corrosion. Depending on the type of use of the prestressed reinforced concrete rope, the outer casing pipe can of course also be made of normal steel, which is subsequently coated with a corrosion protection.

The use of the outer casing pipe as lost formwork and as protection against corrosion-triggering influences results in a pre-tensioned reinforced concrete rope of extremely high quality, whereby the cladding pipes and prestressing steel are already very well protected against dirt and corrosion during the construction period, so that good connection surfaces are preserved and Concreting a perfect connection of concrete and steel is proven. Due to the use of reinforced steel cladding pipes, which already have a certain buckling stiffness and bending stiffness, it is possible that the steel parts can be subjected to tension in the construction state even before the concrete is introduced. It is possible to relieve the steel pipes that are subject to tensile stress by slightly prestressing the prestressing steels.

When assembling the steel parts for such a prestressed reinforced concrete rope, they can, as usual, be assembled in sections, the individual sections of the outer casing tube being welded to one another and the cladding tubes being screwed together by screwed sockets. However, it is also possible to provide push-in sleeves for the sheathing of the cladding tubes and to screw the sections of the outer jacket tubes together.

The outer casing pipes are provided at certain intervals with openings through which the concrete is poured. These openings are closed with a lid, which is preferably screwed on.

In Fig. 3, a side view of a suspension bridge is shown in perspective, in which the pre Tensioned reinforced concrete ropes according to the invention are used for the supporting ropes and the hanging bars. In the area of the junction between the suspension cables and the hanging rods, the outer casing tubes are provided with a connecting piece 20 for welding or screwing on the outer casing tubes of the hanging rods. In the upper part of the outer casing tube of the suspension cable there is an opening 24 which can be closed with a cover 22 and through which a tensioning head 26 can be inserted. This clamping head 26 can be provided with an annular shoulder 28 which rests on a collar 30 of a ring 32 which is preferably welded into the outer casing tube.

The production of a suspension bridge using the prestressed reinforced concrete cables according to the invention enables the production of a prestressed concrete suspension bridge for the first time with relatively simple means. When building the bridge, the pylons are first created and a mounting rope is tensioned in a conventional manner over which a work platform is suspended. To assemble the suspension cable, the outer casing tube 10 is suspended in sections with the cladding tubes mounted inside the bulkheads 11 and the cladding tubes are screwed together at the joints by means of sleeves. The joint of the outer casing pipe sections is welded. In this way, all metal parts of the suspension cable are mounted, with outer casing tube sections being attached to the nodes according to the structure according to FIG. 4. Due to the bulkhead guidance of the cladding tubes consisting of steel tubes and their sealing and the welding of the individual outer jacket tube sections, a very stable structure suspended from the pylons is created which is already capable of absorbing considerable loads. The prestressing steels are either inserted in sections in the cladding tubes during assembly of the outer jacket tube sections or, after the outer jacket tube has been completed, are threaded into the cladded tubes which are jointed together. At the nodes between the suspension cable and the hanging rods, the outer jacket tube provided for the hanging rods with the bulkhead-guided cladding tubes is then suspended and screwed onto the connecting piece 20. The cladding tubes running in this section of the outer jacket tube are screwed into the clamping head 26. The suspended outer casing pipes of the hanging rods are closed at the bottom, so that after the metal parts have been assembled, the outer casing pipe of the suspension cable and that of the hanging rods can now be concreted.

The use of steel pipes for the cladding pipes and the welding of the outer casing pipe sections to one another creates a very stable structure that is easily able to take up the entire concrete load inside the outer casing pipes. If it should be desirable, however, some of the prestressing steels can be prestressed before the concrete is poured out and / or during the pouring out of concrete. After concreting the suspension cable and at least partially concreting the suspension rods, the longitudinal rails of the bridge are either created from the pylons in the free porch or suspended from the suspension rods as prefabricated parts. After completing the side rails, the cross members are installed and the road slab is completed. It is also envisaged that during these construction measures for the production of the carriageway slab the suspension cable will be partially pretensioned or the pretension will be increased further. After completion of the track slab, both the suspension cables and the hanging bars are pre-tensioned and the prestressing bars are concreted in by injecting concrete.

A suspension bridge manufactured according to the method according to the invention using the prestressed reinforced concrete ropes with an outer casing pipe offers the advantage of extraordinary economy due to the lowest maintenance costs when using stainless steel for the outer casing pipes, since the outer casing pipes influence the concrete, be it due to weather conditions or prevented by other influences such as salt water. In addition to the fact that the prestressed prestressed concrete cables according to the invention with the outer casing pipes made of stainless steel leave a very attractive visual impression, the method also offers the possibility of producing such a prestressed concrete suspension bridge in an extremely economical manner, since the outer casing pipes are used as lost formwork for the supporting cable and the hanging bars Find. The structural design of the outer casing tubes with the bulkhead-made cladding tubes made of steel tubes makes the manufacture of the supporting rope and hanging rods extremely easy, because when using conventional formwork parts that have to be assembled and disassembled, it is hardly possible to use the supporting rope or the Concrete hanging bars without additional sloping bracing or additional supporting structures. By using the cladding tubes made of steel tubes, which are also guided in bulkheads along the inner wall of the outer casing tube, there is a very stable and stable construction of the suspended metal parts even before concreting, which can be kept in its final position during concreting without support or the like . It is also possible to set the position of the supporting side exactly in the position in which the concrete is poured in and hardens during concreting. The outer casing pipes can be relieved of strain by slightly pretensioning the metal structure hanging between the pylons, so that relatively thin sheets, e.g. in the order of 8 to 10 mm for stainless steel for bridge constructions, can be used, the diameter of the suspension cables being of the order of magnitude from 0.8 to about 1.2 m and the hanging rods with a diameter of about 0.4 to 0.7 m for can move such bridge structures of medium size.

The abutment of sections of the outer casing tube shown in FIG. 5 is particularly suitable for outer casing pipes with a large diameter, such as are provided for the suspension cables of suspension bridges.

At the end of the pipe section, a bulkhead 40 is attached, through which the cladding tubes 12 run at such a distance from the outer casing tube 10 that the two bulkheads 40 of two sections lying against one another can be screwed together with bolts 42. This makes assembly possible regardless of the execution of the weld 18. Since the diameter of the inner bore of the bulkhead is at least 0.6 m in the case of an outer casing tube of approximately 1 m in diameter, the screws are accessible.

Claims (5)

1. Posttensioned steel reinforced concrete cable, consisting of steel tendons (16) in conduits (12) which are embedded in concrete, and being characterized in that the concrete is covered by a steel jacket tube (10) which during construction serves as lost form, and that the conduits (12) which run through steel partitions (11) consist of steel pipes which can be stressed by tension or compression.

2. Posttensioned steel reinforced concrete cable, according to claim 1, characterized in that the jacket tube (10) is equipped with apertures which can be tightly closed, and which serve to pour the concrete in sections.

3. Posttensioned steel reinforced concrete cable, according to claims 1 and 2, characterized in that said posttensioned steel reinforced concrete cable is used for suspension cables and vertical hangers of a suspension bridge.

4. Posttensioned steel reinforced concrete cable, according to claims 1 through 3, characterized in that said posttensioned steel reinforced concrete cable is used for stays og a stay cable bridge.

5. A method for the application of posttensioned steel reinforced concrete cable according to claims 1 through 3 in the construction of a suspension bridge by aid of a catwalk hung from a temporary cable laid over the pylons, being characterized inthat the jacket tube (10) for the suspension cables, containing conduits (12) held in place by partitions (11), is hung in sections onto the temporary cable laid over the pylons; that the conduits (12) are connected by sleeves, and the jacket tube (10) sections are bolted or welded together; that the jacket tubes (10) for the vertical hangers, containing conduits (12) held in place by partitions (11), are lowered from the catwalk; that postten- sioning tendons (16) are inserted into the conduits (12) of the suspension cable and of the vertical hangers; that the voids within the jacket tubes (10) of the suspension cables and, as need be, of the vertical hangers, are filled with concrete; that the suspension cables and the vertical hangers are posttensioned step by step according to the load; that the longitudinal girders of the bridge are hung onto the vertical hangers, either in cantilever construction or as prefabricated parts, and the crossbeams and the driveway slab are produced subsequently; and that the suspension cables and the vertical hangers are fully posttensioned and then the conduits (12) grouted by way of injection.

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